BRPI0619027A2 - ink for the engraving steel matrix printing process, process for the manufacture and use thereof, safety document and its manufacturing process - Google Patents

Abstract

INK FOR THE PRINTING PROCESS IN ACTION MATRIX BY RECORDING, PROCESS FOR MANUFACTURING AND USING IT, SAFETY DOCUMENT AND ITS MANUFACTURING PROCESS. The present invention relates to a pasty ink for the embossing steel matrix printing process having a viscosity value above 3 Pa.S, preferably above 5 Pa.S at 40 <198> C and comprising an infrared absorption material, wherein said infrared absorption material is a transition element compound whose IR absorption is a consequence of electronic transitions within the d-envelope of the transition element atoms or lons.

Description

Report of the Invention Patent for "INK FOR THE STEEL PRINTING PROCESS FOR RECORDING, PROCESS FOR MANUFACTURING AND USE OF THEREOF, SAFETY DOCUMENT AND ITS MANUFACTURING PROCESS".

The present invention relates to the field of paints and coating compositions. In particular, it is about an ink for the engraving steel matrix printing process (Cobreplate-, Intaglio-), which is used for printing paper money and other security documents. More particularly, the Intaglio ink of the present invention is designed to selectively absorb radiation in parts of the 'infrared' optical spectrum while being transparent to other parts of it.

Compounds and coatings which absorb radiation in the 'infrared optic' range of the electromagnetic spectrum, that is, between a wavelength of 700 nm and 2500 nm, are known to those skilled in the art. Such materials are used as absorbers of solar energy, as well as for producing machine readable hidden clues about objects or documents, for automatic processing or authentication of said objects or documents by machines.

Throughout the present description, the terms 'infrared' or 'IR' are used to denote the spectral range between a wavelength of 700 nm and 2500 nm. The term 'visible' shall mean the spectral range between a wavelength of 400 nm and 700 nm. The term 'ultraviolet' or 'UV' will apply to wavelengths which are shorter than 400 nm. In addition, the terms 'near infrared' or 'NIR' are used to denote the spectral range between a wavelength of 700 nm and 1100 nm, which corresponds to the radiation which is detectable by usual silicon photodetectors.

Throughout the present description, the terms engraved steel matrix printing process, Cobreplate printing process and Intaglio printing process are used interchangeably for the same printing technique.

A first group of patents on infrared-related printing technology was exclusively related to process aspects: US 3,705,043 (Zabiak) discloses an infrared absorbing (IR absorbing) inkjet printing ink composition for printing machine-readable barcodes. At the time of this disclosure (1972), bar code reading equipment was, for technical reasons, restricted to the 'near infrared' (700 nm - 1100 nm) range of the spectrum; For this reason, an infrared-absorbing organic nigrosin dye has been added to the paint to make it 'machine visible' as well. A similar technical purpose was considered in US 3,870,528 (Edds et al., IBM) and US 4,244,741 (Kruse, US Postal Service); This latter patent teaches the use of a reduced heteropoly (phosphomolybdic) acid as an inorganic infrared absorber. It can be summarized that these publications do not refer to the use of IR-absorbing substances in safety markings.

A second group of publications relates to security documents: EP-AO 552 047 (Nishida et al., Hitachi Maxell Ltda.) Discloses a security document bearing a printed infrared absorption mark comprising a colored concealment layer for hide the IR absorbing safety element in the visible spectral range of 400 nm - 700 nm. IR absorbers according to EP-A-O 552 047 should be used in conjunction with concealment layers which camouflage their existence and location to the naked eye. EP-AO 263 446 (Abe et al., Dainichiseika Color & Chemicals Mfg. Co. Ltd.) discloses an anti-copy printing comprising secret information about a security document, as well as a method for producing said printing, wherein a black ink IR-absorbing is additionally used and in conjunction with standard IR-transparent four-color process inks. 'IR-absorbing black' is preferably charcoal black, which absorbs without discrimination over the infrared spectral range and is fully visible, while 'IR-transparent black' is an organic dye which absorbs only in the visible range of the spectrum.

In the field of automatic banknote processing, IR absorption plays an important role. Most currently circulating paper money carries not only visibly colored prints, but also specific characters which are only detectable in the infrared part of the spectrum. Generally, these IR-characters are implemented for use by automated paper money processing equipment in banking and commercial applications (automatic teller machines, vending machines, etc.) to recognize a banknote. paper money and to verify its authenticity, in particular to discriminate it from replicas made by color copiers. WO-A-04/016442 (Banque de France) is about documents protected by an infrared absorbing material.

The visible (black) appearance of infrared absorbing inks according to EP-A-O 263 446 is perceived as a disadvantage in safety application where IR absorption should be used as an additional invisible feature, ie concealment. One way to overcome this difficulty can be found by camouflaging IR-absorbing ink through overprinting or by placing pairs of IR- and IR-transparent inks having the same visible color; however, the latter option imposes a constraint limitation on the document designer since it is not compatible with light shades.

Another group of patents disclose invisible IR absorbers which can be used in all shades of paint (including white) without contributing to their visible appearance: EP-AO 608 118 (Yoshinaga et al., Canon K.). discloses a medium (such as a banknote, security document, etc.), recorded with invisible information, as a machine-readable means of recognition for security documents, in order to prevent them from being copied to security machines. copy. Recording is performed using near-infrared absorption cyanine-type organic materials, which are colorless and transparent in the visible part of the spectrum and thus invisible to the human eye. A similar approach was taken by Tashima and others, Dai-nippon Printing Co. Ltd., who reported the use of Ytterbium Phosphate (YbPCU) as an invisible IR absorbing safety element, as well as corresponding inks and coating compositions. - material containing the same, together with security documents and safety standards which may be obtained with it (JP 08-143853 A2; JP 08-209110 A2; JP 09-030104 A2; JP 09-031382 A2; JP 09 -077507 A2; JP 09-104857 A2; JP 10-060409 A2). Finally, US 5,911,921 (Takai et al; Shin-Etsu Chemical Co., Ltd.) discloses an even smaller infrared reflectivity non-stoichiometric ytterbium phosphate to be used as an IR-absorbing safety material.

The organic and inorganic IR absorbers of this latter group of documents thus outweigh the disadvantages of the visible coloration of the IR absorber; However, there is another deficiency related to its use, namely the limited spectral width of the infrared absorption bands visualized by the organic cyanine dyes and the IR absorber YbPO4. Detecting (reading) narrowband IR absorbing characters notably requires detection equipment particularly adapted to read the precise absorption wavelength in question and, in the case of YbPO4, the use of a relatively high concentration of IR-absorbing material in the print ink.

A large number of different models of paper money processing equipment for many suppliers worldwide are currently on the market. This equipment, although it allows checking banknotes for IR absorption, is not by working at one and the same IR wavelength; an 'IR color standard' analogous to the CIELAB standard used in visible colorimetry does not actually exist.

Limited band IR absorbers, therefore, are not compatible with generic paper money processing applications because of compatibility with existing processing equipment. Notably, an adaptation of existing paper money processing equipment in banking and vending applications to change to a new type of IR-absorbing security element is not normally possible.

On the other hand, the classic option of using carbon black as an indiscriminate broadband IR absorber has the aforementioned shortcoming of restricting the banknote designer to merely dark or black shades. To this is added the general availability of such materials; thus, carbon black, although an IR absorber, cannot be considered a safety material. The same applies to semimetallic graphite material, the use of which as an IR-absorbing pigment on safety documents was disclosed by Mürl in WO-A-98/28374.

Ideally, the IR absorber for paper money processing applications should be transparent in the visible range (400 nm to 700 nm) to allow it to be used on all types of visibly colored inks and also on markings. which are invisible to the naked eye and show strong absorption in the near infrared range (700 nm to 1100 nm) to allow their easy recognition by standard paper money processing equipment (based on silicon IR photodetectors, the which are sensitive up to 1100 nm). The IR absorber should furthermore be transparent again slightly in the range of 1100 nm to 2500 nm to allow discrimination of the specific security character on paper money from a simple graphite or black print. which absorbs indiscriminately over the entire IR range. Such discrimination can be performed, for example, by simply checking the transparency in the region of 1100 - 2500 nm using an appropriate photocell (Ge, InGaAs, etc.).

Steel matrix printing (Cobreplate-, Intaglio-) is a specific method for producing government issued paper money and other high security documents. Intaglio printing machines are expensive and heavy equipment which is otherwise not available for commercial printing applications and which is exclusively used in a few high security printing facilities in the world. As a consequence, even a modestly sophisticated sophistication security character can be raised to the high security level if it is applied through an Intaglio printing process. For prior art relating to inks for the steel matrix printing process see EP-A-O 340 163; EP-A-O 432 093; US 4,966,628; US 5,658,964; as well as applicant's WO 02/094952; the contents of these documents being included herein by reference.

Intaglio security printing inks are characterized by their pasty consistency (having a high viscosity value) of more than 3, preferably more than 5 Pascal * sec (Pa's) at 40 ° C) and in particular for their high solids content, typically over 50% by weight. Security documents, such as banknotes, must also be durable and withstand sunlight and environmental influences (ie, moisture, oxygen, washing and commonly available solvents and chemicals). Particularly well-resistant ink formulations comprising high performance epoxy ester or urethane binder resins are therefore used to print such documents. Pigments, fillers and other solids comprised in an Intaglio paint are, for the same reason, preferably chosen to be inorganic compounds; Proven high strength organic pigments can be used as well, however.

It is an object of the present invention to provide an Intaglio printing ink that meets the above requirements.

It has now surprisingly been found that the above objective is solved by an ink for the engraving steel matrix printing process, said ink comprising a polymeric organic binder, an infrared absorbing material and, if required, a solvent and / or filler metal, said paint having a pasty consistency with a viscosity value of at least 3, preferably 5 Pa's at 40 ° C and wherein said infrared absorbing material comprises element atoms or ions. infrared absorption is a consequence of electronic transitions within the d-envelope of atoms or ions of the transition element.

Surprisingly, a class of materials have been found which are suitable as broadband IR absorbers in Intaglio1 printing inks that meet these requirements and overcome the deficiencies of narrowband IR absorbers and graphite or black IR absorbers. indiscriminate coal. Said infrared absorbing materials, which may be organic or inorganic in nature, are characterized by the fact that they contain specific chemical elements having an incomplete electronic d-envelope (i.e. atoms or ions of transition elements) and whose infrared absorption is a consequence of electronic transitions within said d-envelope of the atom or ion. Selected compounds of transition element atoms or ions have been found to absorb in the NIR range (700 nm to 1100 nm), while being nearly transparent in the visible range (400 nm to 700 nm) of the spectrum, as well as in some range between 1100 nm and 2500nm. These materials, despite the fact that they show only moderately strong absorption in said NIR1 range can be applied through Intaglio printing, so that a sufficient amount of IR absorbing material is transferred over the security document to result at a useful IR contrast (absorption density).

Electronic d-d transitions, which occur within the incomplete d-envelope of a transition element atom or ion, are known to those skilled in inorganic spectroscopy. Reference is made in this context to Α. Β P. Lever, "Inorganic Electronic Spectroscopy", 2nd edition, "Studies in Physical and Theoretical Chemistry, Vol. 33", Elsevier, Amsterdam, 1984, Chapter 6. The terms 'transition element' or 'transition metal' apply in the context of the present invention the chemical element sequences # 22 (Ti) to 29 (Cu), # 40 (Zr) to 47 (Ag) and # 72 (Hf) to 79 (Au) of the Periodic System, with particular emphasis to the first transition series (Ti, V, Cr, Mn, Fe, Co, Ni, Cu).

Preferably, the transition element in the infrared absorbing compound is present in the form of an ion, such as a titanium (III), vanadium (IV) = vanadyl, chromium (V), iron (II), nickel ion (II), cobalt (II) or copper (II) (corresponding to the chemical formulas Ti3 +, VO2 +, Cr5 +, Fe2 +, Ni2 +, Co2 + and Cu2 +). More than one transition element atom or ion, as well as other atoms or ions (cations or anions) may furthermore be present in said compound, either for structural reasons or to exploit a cumulative effect.

Materials whose light absorption is a consequence of electronic transitions within the d-envelope of transition element atoms or ions exhibit a merely moderate specific absorption. Their lack of specific light absorption must therefore be compensated for by a correspondingly high amount of material, that is, a sufficiently thin layer of material must be present to produce the required absorption property. The prior art transition-wrap-based IR absorption materials have therefore been applied in a thin coating (IR-absorbing inks for solar panels) or used as a filler metal in the mass of a plastics material. .

Infrared absorbers based on d-wrap transition element have not, however, been used so far in ordinary printing applications, where the available layer thickness is merely a few micrometers in offset printing and up to a maximum of 10 to 15 micrometres of dry residue in screen printing applications and where only a fraction of the total layer thickness represents the pigment load. Under such restrictions, those skilled in the ink formulation technique prefer to use a container absorbing material which exhibits high specific infrared absorption in order to obtain the desired result with a reduced amount of material.

It has been found that using the Intaglio printing process, it is possible to transfer a thin layer (up to 50 micrometers) of a high solids ink onto a substrate. Thus, using the Intaglio printing process, it is possible to apply a sufficient amount of said wrap-around transition element-based IR absorbing materials onto a document to result in useful infrared contrast. In addition, disclosed IR-absorbing materials are not commonly available for printing applications, making them suitable for use in secure printing due to the absence of readily available counterfeiting opportunities.

The infrared absorption properties of transition element compounds are known and already exploited in certain areas of technology. Iron (II) and copper (II) compounds having a Fe (2+) or Cu (2+) ion in an appropriate chemical environment have been proven to be efficient broadband IR absorption materials in the near range. infrared. Appropriate iron (II) or copper (II) compounds are transparent in the visible range of the spectrum - at most lightly yellowish or bluish in color - and stable under ambient conditions (ie exposure to oxygen and moisture) . A "suitable chemical environment" is, for example, a phosphate or polyphosphate ion or, more generally, a phosphorus and oxygen containing group; In many of the prior art IR-absorbing materials, a Cu (2+) or Fe (2+) ion is actually bound by an oxygen atom to a phosphorus atom, forming a sequence. of MOP atom.

US 4,296,214 (Kamada et al., Mitsubishi Rayon Co., Ltd.) discloses a sunscreen acrylic resin having copper (II) containing copolymerized acrylic diphosphonate esters therein. US 5,466,755 (Sakagami et al., Kureha Kagaku Kogyo Κ. K.) discloses a plastic optical filter material based on acrylic copolymer containing monohydrogen phosphate diester and dihydrogen phosphate monoester groups in which copper ions (II) and / or iron (II) are incorporated. US 6,410,613 (Ohnishi et al., Kureha Kagaku Kogyo Κ. K.) is about other IR-absorbing phosphate ester polymers comprising copper ions. These polymeric materials are useful as near-infrared absorbers (filters) in the 700 nm to 1200 nm length range, but they have so far not been used in printing inks.

US 5,236,633 and US 5,354,514 (Satake et al., Jujo Paper Co., Ltd.) describe near-infrared absorption materials based on a transparent thermoplastic polymer (polymethacrylate, polycarbonate, polyethylene, vinyl chloride). , etc.), an organic thiourea compound and a copper compound, which are fused together to provide a visible-transparent (slightly bluish) IR-absorbent plastic material. US 5,723,075 (Hayasaka, Nippon Paper Industries, Co., Ltd.) discloses similar technology except that dimerized organic thiourea derivatives are used.

U.S. Patents 2,265,437 and US 5,800,861, issued to The Sherwin-Williams Company, disclose the use, among others, of IR-absorbing copper phosphate, basic copper phosphate and coated copper pyrophosphate. for the production of passive solar collectors and the like. These coatings are characterized by the fact that they have, besides their visible absorption, a wide absorption band in the region of 700 nm to 1200 nm.

Phosphate and / or fluoride containing glasses comprising copper (2+) ions have also been used as IR absorbers, in particular for IR cut filters in the optical industry. US 5,173,212 (Speit et al., Schott Glaswerke) and US 2004/0082460 (Yamane et al., HOYA Corporation) disclose corresponding glass formulas and the resulting light absorption spectra.

JP 05-279078 A2 (Manabe et al., Asahi Glass Co. Ltd.) discloses a near infrared absorption material for screen printing application, which is a colorless copper (II) phosphoric acid glass powder , mixed with a resin material, used for reading on a near infrared laser light reading machine. JP 06-207161 A2 (Usui et al., Asahi Glass Co. Ltd.) discloses another screen printing ink which contains copper (II) phosphates as a semiconductor laser light absorber (810 nm). JP 05-093160 A2 (Matsudaira, Toppan Printing Co. Ltd.) discloses an invisible two-component classified information printing ink. The ink comprises, as an IR absorber, a phosphate glass containing iron (II) and / or copper (II) oxide (from Asahi Glass Co. Ltda.). JP 06-107985 A2 (Matunda and others, Toppan Printing Co. Ltd.) discloses another two-component IR absorbing ink based on white copper (II) phosphate and / or copper / iron. (II) vitreous as the IR absorber. These inks are used for machine-readable barcode printing on security documents, such as long-term credit cards, ID cards, etc., where printed information must be read by a laser. near the infrared semiconductor.

Approved action matrix printing inks (copper and intaglio star). Understanding said classes of copper (II) or other transition element atom or ions contained in broadband near-infrared absorption compounds have not, however, been present at this time.

The ink of the present invention for the engraving steel matrix printing process comprises an organic binder resin, preferably of the high strength epoxy ester, urethane alkyd or UV curing type, as well as an absorption material. infrared according to the invention, optionally one or more pigments to produce the desired visible color, optionally fillers and / or solvents to adjust the viscosity of the paint to above 3 Pa.s, preferably above Pa.sa 40 ° C and optionally other additives such as desiccants (dryers), photoinitiators, waxes and rheological additives. Said infrared absorption material is a transition element compound whose IR absorption is due to electronic transitions within the d-envelope of the transition element atoms or ions. The formulation of Intaglio inks and the materials commonly used to make Intaglio inks (ie binders, fillers, solvents, pigments and other paint additives) are known to those skilled in the art and need not be further discussed here.

The origin of IR absorption in Intaglio inks disclosed herein is different from that of the or YbPO4 absorbent disclosed by Tashima et al. (E.g. JP 08-143853), which is a narrow band absorption and due to a electronic transition into the rare earth ion envelope (Yb (3+)). It is also different from that of the reduced heteropoly acids (phosphomolybdic acids) disclosed in US 4,244,741, which is due to cooperative electron charge transfer transitions within a molecular complex ion rather than a transition within the d-wrap of molybdenum atom isolated.

The source of IR absorption of the Intaglio inks disclosed herein is furthermore clearly evident from that of EP-AO 608 118 narrowband near-infrared cyanine-type organic dyes, as well as that of the nigrosine dyes of US 3,705,043 and other organic dyes such as IR-absorbing phthalocyanines and their derivatives. The light-absorbing properties of the mentioned organic dyes are remarkably correlated to their extended molecular electronic π-system, involving carbon atoms and other electronic β-envelopes. Such extended π-systems, however, have the deficiency of increased chemical reactivity; Apart from a few exceptions, most known organic dye molecules, for this reason, are not very stable under environmental influence (light, moisture, atmospheric oxygen).

The IR absorbers of the present invention have neither cooperative interatomic or interionic absorption effects of atoms or ions within solid state molecules or compounds, such as in the interval-charge charge transfer bands of 'valence-mixed' compounds ( Prussian Blue, etc.) or with the absorption of the semiconductor materials (GaAs, etc.); in contrast, the compounds considered here rely solely on the intra-atomic (respectively intra-ionic) property of electronic d-d transitions. Said d-d transitions are primarily a property of isolated atoms or ions, since they are to some extent also influenced by the chemical environment or atom or ion.

Preferred IR absorption materials in the context of the present invention are compounds containing iron (II) and / or copper (II), for example the phosphates of said elements and preferably in the form of a solid state compound for maximum durability. Alternatively, however, the atoms or ions of the IR-absorbing transition element may also be attached to a polymeric binder component of the ink, in particular if the binder component contains transition element-specific binding sites, preferably for Cu (2+), and / or for Fe (2+). Said binding sites may be phosphate or phosphonate groups, preferably monohydrogen phosphate diester groups, which are crosslinked to or grafted onto a polymeric parent moiety. Alternatively, the IR absorption complex of a transition element atom or ion and a binding site may simply be contained in the polymer such as, for example, an organic thiourea - copper (II) complex dissolved in binder.

In the context of the present invention, a preferred solid state IR absorber comprising the IR-absorbing transition element atoms or ions is a crystalline compound composed of one or more cations and one or more anions. Preferred anions are selected from the rock-forming anions, that is, those which form insoluble oxide minerals with a wide variety of cations, such as hydroxide, oxide and fluoride anions, as well as various borates, carbonates, aluminiums. minates, silicates, phosphates, sulphates, titanates, vanadates, arsenates, molybdates and tungstates. At least one anion is preferably selected from the group consisting of phosphate (PO43 "), hydrogen phosphate (HPO42"), pyrophosphate (P2074 ~), metaphosphate (P3093 '), polyphosphate, silicate (SiO44 "), polysilates. condensate, titanate (Ti032 ~), condensate polytitanates, vanadate (VO43 "), condensate polyurate, molybdate (MoO42"), condensate polyurate, tungstate (WO42 "), condensate polyturate, fluorine (F) , oxide (02 ") and hydroxide (OH").

Preferred IR absorption cations, in combination with said anions, are iron (II) (Fe2 +) and copper (II) (Cu2 +), either alone or in solid solution with their IR-inactive mineralogical counterparts, for example with magnesium. (II) (Mg2 +) for iron (II) and zinc (II) (Zn2 +) for copper (II).

Crystalline IR-absorption compounds useful in the context of the present invention are those which do not lose part of their composition, for example including crystallization water, when heated to a moderately high temperature, that is, to a temperature not exceeding 400 QC. In fact, it has been found to be advantageous to use dehydrated compounds respectively to pre-dehydrate those compounds which contain crystallizing water or otherwise lossy groups by heating them in cross-linking agent. at a temperature between 200 ° C and 400 ° C for about one hour to about four hours (depending on the compound in question) until a constant weight is reached.

Specifically, the following compounds may be used in the invention: copper (II) fluoride (CuF2), copper hydroxyfluoride (Cu-FOH), copper hydroxide (Cu (OH) 2), copper phosphate (CU3 (PO4) 2) * 2H20), anhydrous copper phosphate (CU3 (PO4) 2), basic copper (II) phosphates (eg Cu2PO4 (OH), "Libetenite" whose formula is sometimes written as Cu3 (PO4) 2 * Cu (OH) 2; Cu3 (PO4) (OH) 3, "Cornetite", Cu5 (PO4) 3 (OH) 4, "Pseudo malachite", CuAI6 (PO4) 4 (OH) 8 * 5H20 "Turquoise", etc. .), Copper (II) Pyrophosphate (Cu2 (P2O7) * 3H20), Anhydrous Copper (II) Pyrophosphate (Cu2 (P2O7)), Copper (II) Metaphosphate (Cu (PO3) 2, more correctly spelled as Cu3 (P3Og) 2), iron (II) fluoride (FeF2MH2O), anhydrous iron (II) fluoride (FeF2), iron (II) phosphate (Fe3 (PO4) 2 * 8H20, "Vivianite"), phosphate lithium iron (II) (LiFePO4, "Trifilite"), sodium iron (II) phosphate (NaFePO4, "Maricite"), iron (II) silicates (Fe2SiO4, "Faialite"; FexMg2 ^ SiO4, "Olivine"), carb iron (II) onate (FeCO3, "Anquerita", "Siderita"); nickel (II) phosphate (Ni3 (PO4) 2 * 8H20) or titanium (III) metaphosphate (Ti (P3O9)). In addition, the crystalline IR absorber may also be a mixed tonic compound, where two or more cations are participating in the crystal structure, as for example in Ca2Fe (PO4) 2 * 4H20, "Anapaita". Similarly, two or more anions participate in the conformal structure in the mentioned basic copper phosphates, where OH (-) is the second anion or even together as in iron / magnesium phosphate fluoride MgFe (PO4) F1 "Wagnerite".

The solid state IR absorber may furthermore be a glass comprising the IR-absorbing transition element ions or atoms. Preferred glasses are of the types comprising phosphate and / or fluoride, in which there is coordination of the transition element ions or atoms to the phosphate and / or fluoride anions present in the glass. These anions are notably situated at the lower end of the "spectrochemical series", that is, they provide low energy d-d transitions in transition element ions by pushing the absorption bands of the ions into the infrared. Like the "spectrochemical series", reference is made to Á. Β P. Lever, "Inorganic Electronic Spectroscopy", 2nd edition, "Studies in Physical and Theoretical Chemistry, Vol. 33", Elsevier, Amsterdam, 1984, Chapter 9 and references cited therein.

IR-absorbing glasses which may be introduced into a correspondingly powdered form in the Intaglio ink disclosed herein are, for example, those of JP 05-279078 A2 and JP 05-093160 A2, documents which have already been cited above.

Pigments and additives for Intaglio ink formulations have a statistical particle size, preferably not exceeding 50 micrometers, more preferably not exceeding 20 micrometers, most preferably not exceeding 10 micrometers. No individual particle in general should exceed a size of 100 micrometres (maximum cut-off limit), an objective which is usually achieved through a final sorting (screening) operation. Very large particles, even in small numbers, lead to noticeable problems with the printing press as ink tends to drip from the engraving.

The specific absorption in the 'infrared optical' range (i.e., between 700 nm and 2500 nm) of the infrared absorbing material which is exploited in the Intaglio ink of the present invention is thus merely a consequence of intra electronic dd transitions. -atomic or intraionic. The absorbent material may, however, in addition to this exploited IR absorption, exhibit other dd transition bands in the visible range (i.e. between 400 nm and 700 nm) as well as all types of absorption bands in the ultraviolet region. spectrum (ie below 400 nm).

The IR absorbing materials which are used in the Intaglio paint of the present invention are, however, different from the prior art transition metal pigments, such as nickel and cobalt pigments used in decorative coatings (cobalt blue). ', etc .; US 3,748,165), or the iron-based black, red and yellow pigments used in classic coating and printing applications. In such prior art transition metal pigments, a visible absorption effect is intentionally intended and exploited. The basic idea of the present invention, however, is to rely on IR-absorbing pigments which are not, or at most, only poorly colored in the visible range of the spectrum (400 nm to 700 nm) so as to be compatible with all visible shade of ink and useful for invisible markings.

Preferred IR-absorbing materials in the ink of the present invention, therefore, are those which do not substantially absorb in the visible range of the spectrum (400 nm to 700 nm), that is, those whose diffuse reflectance brightness value (L *). CIE (1976) is greater than 70, preferably greater than 80 as measured on pure powder.

To obtain a sufficiently strong absorption effect, IR-absorbing transition metal atoms or ions must be present in a high concentration in the IR-absorbing material; typically at a concentration of 10% or more, preferably 20% or more, and more preferably 40% or more by weight. The IR-absorbing materials which are used in the Intaglio paint of the present invention are thus different from transition element-containing luminescent compounds such as ruby (AI203: Cr) or metal doped grenades (cf. US 3,550,033). and other crystals used in laser applications. Such luminescent compounds notably contain the emission or sensitization transition metal ions merely at low concentrations which are suitable for producing said luminescence effects.

In addition, the Intaglio ink of the present invention should contain the IR-absorbing material at a sufficiently high concentration level to produce a good contrast over the printed document in the said IR range of the spectrum. Useful concentrations of the absorbent material in the paint range from 5% to 70%, preferably 10% to 50%, even more preferably 20% to 50% by weight of the ink; These concentration levels are significantly higher than the concentration levels used in the case of luminescent markers.

Said level of concentration of the IR-absorbing material may furthermore be varied within the inks used on the same document so as to produce lighter and darker infrared zones on the document or to print a figure on it. Hidden infrared halftone, respectively. This may be embodied, for example, by a document bringing at least two IR-absorbing inks according to the invention, wherein said IR-absorbing inks differ in their level of IR absorption.

In another embodiment, the same ink comprising the IR absorber may be printed with an Intaglio plate having zones of different engraving depths. This results, in particular in the case of the mildly absorbed IR transition metal compounds used in the present invention, in lighter and darker infrared zones on the document. This infrared absorption density modulation can, furthermore, be camouflaged by a strong visible absorption pigmentation of the Intaglio ink, so that the difference in embossing depth does not show a difference in visible color.

In addition, the IR-absorbing material of the present invention, which provides a broad absorption profile, can be usefully combined within the same ink with all types of other IR-absorbing materials disclosed in the art and, in particular with IR-absorbing organic materials. Organic IR-absorbing materials having a narrower absorption peak than transition metal-based IR-absorbing materials are particularly preferred in the present context. This combination, in fact, makes it possible to produce an even more complex infrared absorption profile and thereby increase the sophistication and security of hidden marking. Organic IR-absorbing material may also be present in a second ink, printed on the same document, to exploit the resulting machine readable contrast.

The Intaglio IR-absorbing ink of the present invention is preferably used for the production of security documents such as banknotes, passports, checks, titles, ID cards, business letters, stamps, papers. rate, etc. IR-absorbing ink may here be printed as a safety character only or used in conjunction with non-IR-absorbent inks having the same visible hue to produce a hidden IR-absorption pattern. In addition, the IR-absorbing ink of the present invention may be combined on the same document with other IR-absorbing inks having a different composition from that disclosed herein, in particular with inks containing an organic IR-absorber.

A process for the manufacture of an engraving steel matrix printing ink according to the present invention comprises the step of incorporating an infrared absorbing material comprising a transition element atom or ion whose infrared absorption It is a consequence of electronic transitions within the envelope of said transition element atom or ion in a polymeric organic binder along with other optionally required materials.

The manufacture of an Intaglio ink, including adjusting its viscosity and other rheological properties for printing performance and another Intaglio printing process itself is well known to those skilled in the art and need not be further explained. on here.

The Intaglio ink of the present invention will now be further explained with the aid of nonlimiting exemplary embodiments.

Figure 1 shows the IR absorption characteristics of the infrared copper phosphate glass pigment used in example 1 of the present application.

Figure 2 shows the IR absorption characteristics of a white Intaglium paint comprising copper phosphate according to example 2 of the present application.

Figure 3 shows the IR absorption characteristics of "Trifilite" (LiFePO4) iron phosphate used in example 3 of the present application.

Figure 4 shows the IR absorption characteristics of the copper (II) and / or iron (II) phosphate polymers used in example 4 of the present application.

Figure 5 shows the IR absorption characteristics of an Intaglium paint comprising copper phosphate and an additional organic IR absorber according to example 5 of the present application. Example 1:

Ink formulation Oxidative drying medium comprising phosphate glass infrared absorber

(for Intaglio / Copperplate printing process for paper)

Product of addition of tung oil and modified phenolic resin 25.0

with maleic acid in high boiling mineral oil

(PKWF 28/31)

Long Chain Oily Alkyd Resin 7.5

Ink-modified crude tung oil modified alkylphenolic resin 16.0 Solvent 6/9 (S. I. C.)

Polyethylene Wax (mp 130 ° C) 1.5

Calcium carbonate (natural chalk) 13.0

Phosphate Glass IR Absorbing Pigment (*) 25.0

Colored Pigment (**) 5.0

Ink Solvent 6/9 (S.I.C) (**) 6.0

Cobalt Octoate Dryer (11% Metals) 0.1

Manganese Octoate Dryer (10% Metals) 0.1

(*) the ceramic glass IR absorbing pigment was prepared by grinding a phosphate glass IR absorber (Figure 1) according to US 2004/0082460, example 1, to an average particle size of the order 8 to 10 micrometers.

To obtain matching color inks but without the IR absorption characteristic, the IR absorbing pigment was replaced by the same amount by weight of calcium carbonate.

(**) The colored pigment was chosen according to the desired shade, for example:

White C.I. Pigment White 6 Yellow C.I. Pigment Yellow 13 Red C.I. Pigment Red 170 Green C.I. Pigment Green 7 Blue C.I. Pigment Blue 15: 3 Violet C.I. Pigment Violet 23

Black Trichrome Black (CI. Pigment Red 170; C.I. Pigment Yellow 13; C.I. Pigment Blue 15: 3 in appropriate proportion). This pigment mix is an "IR-transparent black" which allows ink to be transparent over the far-infrared optical range. (***) Ink viscosity was adjusted with Ink Solvent 6/9 (Shell Industrial Chemicals) to between 5 and 10 Pa.S at 40 ° C.

Equivalent color pairs of visible-shade inks determined, each shade once with and once without the IR absorber, were prepared each time by mixing all components of the formula except for the dryers together. , and performing two passes over a three-roller shredder to obtain a homogeneous paint. The dryers were finally added and mixed for 15 minutes and the final paint was degassed under vacuum. The viscosity of the paint was adjusted to 10 Pa.S at 40 ° C.

The inks thus obtained were printed with a standard Inglio press on banknote paper in the form of a pattern comprising visible colors and hidden IR-characteristics. IR absorption patterns, useful for processing on paper money machine, could thus be obtained completely regardless of the visible aspect of the document.

Example 2:

Intaglio Ink fed on oxidative drying sheet for aqueous Intaglio copperplate printing process An Intaglio water-containing non-conducting ink is manufactured according to the following formula:

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Deionized water thickened with cellulose ether (MC or 15.0 sod-CMC 2.5% to 3.0%) (***)

(*) The IR absorbing phosphate pigment was dehydrated copper phosphate of the formula Cu3 (PO4) 2, obtained by heating hydrated copper phosphate for 2 hours at 400 ° C in air.

To obtain matching color inks but without the IR absorption characteristic, the IR absorption pigment was replaced by the same amount by weight of calcium carbonate.

(***) Cellulose ether was chosen from the group of Methyl Cellulose (MC) and / or Sodium Carboxymethyl Cellulose (sod-CMC) and used as described by C. Baker, The Book and Paper Group Annual, Vol. 1 , 1982. Equivalent color pairs of white-tinted inks once with and once without the IR absorber were prepared each time by mixing all components of the formula except for the dryer and water together. for 20 minutes at room temperature over a Molteni mixer, then making two passes over a three-roller crusher to obtain a homogeneous paint. The dryer and water were finally added and mixed for at least 15 minutes; The resulting paint was degassed under vacuum over a Molteni mixer. The viscosity of the paint was adjusted to 10 Pa.S at 40 ° C.

Example 3

A cationically polymerizable UV curable paint was manufactured in a classical manner (ie by premixing all the ingredients, then performing two passes on a three-roller crusher) according to the following: formula:

Cationically polymerizable varnish as described in US 44,0 5,658,964

Salt-based starter (CYRACURE UVI 6974-7.0 Union Carbide)

IR-absorbing phosphate pigment (*) 15.0

Colored Pigment (**) 3.0

Smoked Silicon Dioxide (AEROSIL 200 -Degussa) 15.0

Micronized Polyethylene Wax (CERIDUST 9615A— 5.0 Hoechst)

Surfactant (SILWET L 7604-Union Carbide) 1.0

Viscosity Regulator (TRIETHYLENE GLYCOL-Dow 10.0 Chemicals)

(*) The IR-absorbing phosphate pigment was chosen to be lithium iron (II) phosphate (LiFePO4, "Trifilite") having an absorption spectrum as given in Figure 3.

To obtain matching color inks but without the IR absorption characteristic, the IR absorption pigment was replaced by the same amount by weight of calcium carbonate.

(**) The colored pigment was chosen to the desired shade as given in example 1. The paint was adjusted to a viscosity of 12.5 Pa.S at 40 ° C. It showed an excellent light cure response UV as well as a very good dark post cure. The ink was usable on paper and fulfilled all the necessary requirements for engraved steel matrix inks to be used for printing security documents.

Example 4

A UV-curable urethane acrylate attack ink comprising IR absorption phosphate resin:

Reactive urethane acrylate monomer 26.6

IR absorption monomer (*) 20.0

Carnauba Wax 4.0

Sodium Dodecyl Benzene Sulfonate 3.0

UV stabilizer (Florstab UV-I) 2.0

Colored Pigment (**) 5.0

CaCO3 filler metal (***) 33.0

ESACURE® ITX 2.6

IRGACURE 369 3.8

(*) IR absorption monomer was prepared with reference to US 5,466,755, example 1 (cf. Figure 4, curve 1) or example 2 (cf. Figure 4, curve 2); The indicated monomers and the copper (II) salt, respectively the copper (II) and iron (II) salts, were mixed together in heating (60 ° C) without, however, adding a polymerization initiator.

(**) The colored pigment was chosen according to the desired shade as given in example 1.

(***) The ink was adjusted to a viscosity above 5 Pa.S at 40 ° C. It showed good curing response with UV light at a long wavelength.

Printed documents, such as a banknote, passport, check, title, ID or transaction card, stamp, tax document, etc., bearing ink according to the invention, as exemplified in particular by the examples provided, were obtained by printing the ink on a standard Intaglio press. The IR absorption ink has been reprinted as a safety feature alone or, alternatively combined with same-color IR non-absorption inks, to produce hidden IR absorption patterns in addition to the visible characteristics on these documents.

Example 5

Oxidative Intaglio ink with additional specific IR absorption peaks (with reference to figure 5)

Product of adding 25,05 tung oil modified phenolic resin and maleic acid to a high addition point mineral oil (PKWF 28/31)

7.5 Long Chain Oily Someone Resin

Crude Tung Oil Modified Alkylphenolic Resin in Ink 16.0 solvent 6/9 (Shell Industrial Chemicals)

Polyethylene Wax 1.5

Calcium carbonate 19.0

Dehydrated copper phosphate of the formula Cu3 (P04) 2, obtained at 25.0 ° C by heating hydrated copper phosphate for 2 hours at 400 ° C in air

Hexadeca- (3-ethoxy-1-thiophenolate) phthalocyanate-zinc (II) 0.15

Ink solvent 6/9 (Shell Industrial Chemicals) 5.0

Cobalt Octoate (11% Metal) 0.1

Manganese Octoate (10% Metal) 0.1

The ink was prepared as described above.

Claims (23)

An ink for the engraving steel matrix printing process, characterized in that it comprises a polymeric infrared absorption organic binder, said ink having a pasty consistency with a viscosity value at 40 ° C of at least at least -3 Pa.S, preferably at least 5 Pa.S, wherein said infrared absorption material comprises a transition element compound and its infrared absorption is a consequence of electronic transitions within the ds. envelope of atoms or ions of transition element. Ink according to claim 1, characterized in that said transition element is selected from the group consisting of Ti, V, Cr, Mn, Fe, Co, Ni and Cu. Ink according to claim 1 or 2, characterized in that said transition element is an ion selected from the ion group consisting of Ti3 +, VO2 +, Cr5 +, Fe2 +, Ni2 +, Co2 + and Cu2 +. Ink according to any one of claims 1 to 3, characterized in that the infrared absorption material comprising the IR absorption transition element ion or ions is a glass, preferably a glass comprising phosphate and / or fluoride, in which there is a coordination of the transition element ions or ions to the phosphate and / or fluoride ions present in the glass. Ink according to any one of claims 1 to 3, characterized in that the infrared absorption material comprising the IR absorption transition element ions or ions is a crystalline compound consisting of one or more cations. and one or more anions. Paint according to claim 5, characterized in that the anion is phosphate (PO43 "), hydrogen phosphate (HPO42), pyrophosphate (P2O74), metaphosphate (P3O93), polyphosphate, silicate (SiO44"), condensed polysilicates ; titanate (TiO32 "), condensed polytitanates, vanadate (VO43), condensed polyvinylates, molybdate (MoO42), condensed polymolates, tungstate (WO42), condensed polytungstates, fluoride (F"), oxide (O2) and hydroxide (OH). Ink according to claim 5 or 6, characterized in that the infrared absorption material is selected from the group of compounds consisting of copper (II) fluoride (CuF2), copper hydroxyfluoride (CuFOH). ) 1 copper hydroxide (Cu (OH) 2) 1 copper phosphate (Cu3 (P04) 2 * 2H20), anhydrous copper phosphate (Cu3 (PO4) 2), basic copper (II) phosphates (Cu2PO4 (OH) 1 ("Libetenite"), Cu3 (PO4) (OH) 3, ("Cornetite"), Cu5 (PO4) 3 (OH) 4 ("Pseudomalaquita"), CuAI6 (PO4) 4 (0H) 8'5H20 (" Turquoise "), Copper (II) Pyrophosphate (Cu2 (P207) * 3H20), Anhydrous Copper (II) Pyrophosphate (Cu2 (P2O7)), Copper (II) Metaphosphate (Cu3 (P3O9) 2, iron (II) fluoride (FeF2MH2O) 1 anhydrous iron (II) fluoride (FeF2), iron (II) phosphate (Fe3 (P04) 2 * 8H20, Vivianite), lithium iron (II) phosphate (LiFePO4, Trifilite), sodium iron (II) phosphate (NaFePO4, Maricite), iron (II) silicates (Fe2SiO4, Faialita FexMg2_xSi04, Olivine), iron (II) carbonate (FeCO3, Antequita, Sid nickel (II) phosphate (Ni3 (PO4) 2 * 8H20), titanium (III) phosphate (Ti (P3Og)) 1 Ca2Fe (PO4) 2 * 4H20, (Anapaita) and MgFe (PO4) F1 ( Wagnerite). Ink according to any one of claims 1 to 3, characterized in that the infrared absorption material is an IR absorption transition element atom or ion bonded to a polymeric binder component of the ink. Ink according to claim 8, characterized in that the polymeric binder of the ink contains transition element ion specific binding sites, preferably for Cu2 + and / or Fe2 +. An ink according to claim 9, characterized in that said binding sites are phosphate groups which are crosslinked to or grafted onto a main polymeric part. Ink according to any one of claims 1 to 3, characterized in that the infrared absorption material is an IR absorption complex of a transition element atom or ion and a binding site contained in the polymer; preferably an organic thiourea - copper (II) complex dissolved in the binder. Ink according to any one of claims 1 to 11, characterized in that the IR-absorbing material has a diffuse reflectance brightness (L *) CIE (1976) of greater than 70, preferably 70. , greater than 80 as measured on pure powder. Ink according to any one of claims 1 to 12, characterized in that the IR-absorbing material contains IR-absorbing transition element atoms or ions of a concentration of 10% or more; preferably 20% or more and even more preferably 40% or more by weight. Ink according to any one of claims 1 to 13, characterized in that it comprises IR absorption material in a concentration in the range of 5% to 70%, preferably 10% to 50%, even more preferably. % to 50% by weight of the paint. Ink according to claim 14, characterized in that it comprises an additional IR absorber, wherein said additional IR absorber is an organic compound. Ink according to claim 15, characterized in that said additional IR absorber shows a narrower IR absorption peak than the transition metal-based IR absorption material. Process for the manufacture of an embossing steel matrix ink as defined in any one of claims 1 to 16, characterized in that it comprises the steps of: incorporating an infrared absorption material having - comprising a transition element compound whose infrared absorption is a consequence of electronic transitions within the envelope of said transition element atoms or ions in a polymeric organic binder together with other optional materials. Use of an ink for the steel matrix printing or embossing process as defined in any one of claims 1 to 16, characterized in that it is for printing a security document, such as a banknote , a passport, a check, a title, an ID or transaction card, a stamp, a tax document. 19. Security document, such as a banknote, passport, check, title, ID or transaction card, seal, tax document, characterized by the fact that it carries an IR-absorbing ink. as defined in one of claims 1 to 16. A security document according to claim 19, characterized in that it carries at least two IR absorption inks as defined in any one of claims 1 to 16, wherein said IR absorption inks differ in how much. IR absorption levels. Security document according to claim 19, characterized in that it carries an IR absorption ink printed with an Intaglio plate having zones of different engraving depth, so as to result in printed zones of different levels of ink absorption. GO. Security document according to any one of claims 19 to 21, characterized in that it carries at least one other IR absorption ink containing an organic IR absorber. Process for manufacturing a security document as defined in any one of claims 19 to 21, characterized in that it comprises the step of applying an IR absorption ink as defined in any one of claims 1 to 16. , about said security document by means of an engraved steel matrix printing process.